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Molly Beauchemin

The Mold Is Gold: Turning Fall Leaves Into Spring Treasure

As the thermostat drops and the air grows crisp, an essential gardening ritual becomes imminent: raking fall leaves. Many gardeners associate this longstanding chore with lower back pain and pesky gusts of wind, while for others, it’s the perfect way to relax the mind and clear away the detritus of the past so that when spring comes, the garden can begin anew. Once you’ve finished, you probably drag those fat black bags to the curbside – but it turns out that last fall’s trash can be transformed into spring treasure in the form of leaf mold: a potent fertilizer that adds nutrients to the garden.

As a leaf departs from its home in the branches and hits the ground, it begins to decompose. Left untouched, the average leaf takes around two years to decompose completely (the pace may vary depending on temperature, humidity, leaf type, and how exposed the leaf is to the surrounding air). Leaf mold spores form on partially-decomposed leaves, and over the years (and ostensibly, when combined with other yard waste), the greenery breaks down into the black powder you know as compost.

“Leaf mold” doesn’t resemble the funky growths found in water or ceiling tiles: it’s tan, crumbles in your fingers, and smells like plain old dirt. Despite its formlessness, the substrate retains 300 to 500 percent of its weight in water, on average. This makes it a fantastic pillow mulch, ideal for protecting shrubs and roots in the wintertime. Over time, the leaf mold will gradually leech into the soil, releasing its nutrients and improving its quality. Altogether, the leaves of one large shade tree can net almost $50 in plant food!

A circular, woven-wire fence tamped down with wet, freshly-fallen leaves provides an efficient, time-tested option for the modern farmer: if you leave the leaves be in October, they’ll have matured into suitable leaf mold by June. That said, the simplest method for making great leaf mold is the same technique you’ve been doing since the beginning of time. Just put in a few hours’ work, and you’ll have perfect, home-made mulch to last all season: not bad for a mundane chore.

How To Make Leaf Mold

  1. Begin by raking and bagging the leaves as normal, gathering them into small piles. It’s a good idea to do this on a dry day, as excess moisture will interfere with the decomposition process.
  2. Shred the leaves by using a shredder, lawnmower, or other machine.
  3. Bag and place the leaves in an undisturbed, dry location, such as a toolshed or basement.
  4. To ensure proper airflow (and accordingly, mold growth), poke seven holes in the side of each bag with a knife.
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